Ejector

ABSTRACT

An ejector includes a nozzle, a body portion and a pressurizing portion. The body portion has a fluid suction port from which a fluid is drawn by a jet flow of a fluid jetted from the nozzle, and a fluid suction passage through which the fluid drawn from the fluid suction port flows while a flow direction of the drawn fluid is changed. The fluid suction passage has a suction inlet part, a suction space part, and a suction outlet part from which the fluid from the suction space part flows out in a jet direction of the jet fluid. A fluid passage area of the suction inlet part is smaller than an open area of the fluid suction port and a fluid passage area of the suction space part, and the fluid passage area of the suction outlet part is smaller than that of the suction space part.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2008-156331filed on Jun. 16, 2008, the contents of which are incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to an ejector in which a fluid is drawnfrom a fluid suction port by using suction action of a high-speed jetfluid jetted from a nozzle.

BACKGROUND OF THE INVENTION

JP 2004-270460A (corresponding to US 2004/0172966 A1) proposes anejector that includes a nozzle for jetting a fluid at a high speed, afluid suction port from which a fluid is drawn by using suction actionof the high-speed jet fluid jetted from a fluid jet port of the nozzle,and a pressure increasing portion (e.g., diffuser) in which the jetfluid and the drawn fluid are mixed and the pressure of the mixed fluidis increased. Furthermore, the ejector is provided with a taper-shapedneedle that extends from an interior of a fluid passage of the nozzle toan exterior of the fluid jet port of the nozzle concentrically with thefluid passage of the nozzle. The tip portion of the needle is taperedtoward downstream in a jet direction of the fluid in the nozzle.

In the above-described ejector, the fluid is jetted from the fluid jetport of the nozzle to flow along the surface of the needle so that thejet fluid has a suitable expanding shape, thereby improving the nozzleefficiency of the ejector. The nozzle efficiency is an energy conversionefficiency in the nozzle, and is defined as a ratio of a speed energy ofthe jet fluid to an enthalpy difference (expansion energy) between thefluid at the inlet of the nozzle and the fluid at the jet port of thenozzle.

However, according to the studies by the inventor of the presentapplicant, it is difficult to increase a pressurizing amount of thefluid in the diffuser by an amount corresponding to an increased amountof the nozzle efficiency even when the nozzle efficiency is increased.

In order to sufficiently increase the pressurizing amount of the fluidin the diffuser, it is necessary not only to increase the nozzleefficiency but also to reduce a mixing energy loss that is caused whilethe jet fluid and the drawn fluid are mixed.

The mixing energy loss is easily caused when the flow direction (suctiondirection) of the fluid drawn into the ejector is different from the jetdirection of the fluid as in the above ejector. If the suction directionand the jet direction are different from each other in the ejector, theflow direction of the suction fluid needs to be changed to the jetdirection of the jet fluid while the suction fluid and the jet fluid aremixed, thereby causing a velocity distribution in the suction fluid.

When the suction fluid having the velocity distribution is mixed withthe jet fluid, the mixed fluid of the jet fluid and the suction fluidbecomes in an un-uniform state, and thereby the pressurizing amount inthe diffuser is reduced.

SUMMARY OF THE INVENTION

In view of the foregoing problems, it is an object of the presentinvention to provide an ejector, which can reduce energy loss causedwhile jet fluid and suction fluid are mixed, thereby increasing apressurizing amount in a pressurizing portion of the ejector.

According to as aspect of the present invention, an ejector includes anozzle configured to decompress and jet a fluid, a body portion and apressurizing portion. The body portion has a fluid suction port fromwhich a fluid is drawn by a jet flow of the fluid jetted from thenozzle, and a fluid suction passage through which the fluid drawn fromthe fluid suction port flows while a flow direction of the fluid drawnfrom the fluid suction port is changed. In the pressurizing portion, apressure of a fluid mixture between the fluid flowing through the fluidsuction passage from the fluid suction port and the fluid jetted fromthe nozzle is increased. In the ejector, the fluid suction passage isconfigured to have a suction inlet part into which the fluid from thefluid suction port flows, a suction space part in which the flowdirection of the fluid flowing from the fluid suction port is changed,and a suction outlet part from which the fluid from the suction spacepart flows out in a jet direction of the jet fluid. Furthermore, thesuction inlet part has a fluid passage area that is smaller than an openarea of the fluid suction port and a fluid passage area of the suctionspace part, and the fluid passage area of the suction outlet part issmaller than the fluid passage area of the suction space part.

Because the fluid passage area of the suction inlet part is smaller thanthe open area of the fluid suction port, the flow speed of the suctionfluid flowing from the suction inlet part into the suction space partcan be increased than the flow speed of the suction fluid drawn from thefluid suction port. Thus, it is possible to increase the dynamicalpressure of the suction fluid flowing from the suction inlet part to thesuction space part. Therefore, the fluid is disturbed in the suctionspace part, thereby effectively mixing the fluid in the suction spacepart of the ejector. Furthermore, because the flow speed of the suctionfluid after flowing into the suction space part is decreased more thanthe flow speed of the fluid just flowing into the suction space part,the dynamical pressure of the suction fluid is converted to the staticpressure thereof in the suction space part. Accordingly, the suctionspace part can be used for equalizing the pressure of the fluid flowingout of the suction outlet part. In addition, because the fluid passagearea of the suction outlet part is smaller than the fluid passage areaof the suction space part in the ejector, it can prevent the fluid fromflowing out of the suction outlet part before a different in the flowspeed distribution is reduced. As a result, the ejector can reduceenergy loss caused while the jet fluid and the suction fluid are mixed,thereby increasing a pressurizing amount in the pressurizing portion.

The fluid suction port may be connected to a fluid suction pipe in whichthe fluid to be drawn into the fluid suction port flows. In this case,the fluid passage area of the suction inlet part is smaller than a fluidpassage area of the fluid suction pipe. Furthermore, the fluid passagearea of the fluid suction pipe can be gradually reduced as toward thefluid suction port.

For example, the suction inlet part may be an orifice.Alternatively/further, an extending line of a flow direction of thefluid drawn from the fluid suction port may be crossed perpendicularlywith an extending line of the jet direction of the fluid jetted from thenozzle. The suction space part may be provided on an outer peripheralside of the nozzle.

In the ejector, a ratio of the fluid passage area of the suction inletpart to the open area of the fluid suction port may be equal to orsmaller than 0.5, or/and a ratio of the fluid passage area of thesuction inlet part to the maximum fluid passage area of the fluidsuction pipe may be equal to or smaller than 0.5, or/and a ratio of thefluid passage area of the suction outlet part to the fluid passage areaof the suction space part may be equal to or smaller than 0.5.

As an example, the suction space part may be an approximatelycylindrical passage provided on the outer peripheral side of the nozzleto extend in an axial direction of the nozzle, and the suction outletpart may extend coaxially with the cylindrical passage of the suctionspace part and is tapered downstream. Furthermore, the nozzle may belocated to protrude into the suction outlet part from the suction spacepart coaxially with the cylindrical passage, and the suction inlet partmay be open to the cylindrical passage in a direction approximatelyperpendicular to the axial direction of the nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional objects and advantages of the present invention will be morereadily apparent from the following detailed description of preferredembodiments when taken together with the accompanying drawings. Inwhich:

FIG. 1 is a schematic diagram showing a refrigerant cycle device havingan ejector, used for a heat pump water heater, according to a firstembodiment of the invention;

FIG. 2 is a schematic sectional view showing the ejector according tothe first embodiment; and

FIG. 3 is a schematic sectional view showing an ejector according to asecond embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

An ejector 15 and a refrigerant cycle device 10 including the ejector 15according to a first embodiment of the present invention will bedescribed with reference to FIGS. 1 and 2. In the present embodiment,the refrigerant cycle device 10 having the ejector 15 is typically usedfor a heat pump water heater 1 shown in FIG. 1.

The heat pump water heater 1 includes a water circulation circuit 20 inwhich water in a water tank 21 is circulated, and the refrigerant cycledevice 10 which is configured to heat water to be stored in the watertank 21. The water tank 21 is used for temporally storing the hot waterheated by the refrigerant cycle device 10. In the present embodiment, arefrigerant as an example of a fluid circulates in the refrigerant cycledevice 10, and carbon dioxide (CO2) is used as the refrigerant. When thecarbon dioxide is used as the refrigerant in the refrigerant cycledevice 10, the pressure of high-pressure side refrigerant dischargedfrom a compressor 11 becomes higher than the critical pressure of therefrigerant.

First, the water circulation circuit 20 will be described. The watertank 21 is a hot water storage tank made of a metal (e.g., stainlesssteel) having a heat insulating structure, in which high-temperature hotwater can be stored for a long time. Generally, the water tank 21 ismade of a metal having a sufficient corrosion-resistance property.

How water stored in the water tank 21 is supplied to an exterior from ahot water outlet provided at an upper portion of the water tank 21. Thehot water from the hot water outlet of the water tank 21 can be suitablymixed with tap water by using a temperature adjustment valve, and thenis supplied to a using place such as a kitchen, a bathroom or the like.A water inlet is provided at a lower portion of the water tank 21 sothat water such as tap water can be supplied to the water tank 21 fromthe water inlet of the water tank 21.

An electrical pump 22 for circulating water is located in the watercirculation circuit 20. The operation of the electrical pump 22 iscontrolled by control signal output from an electrical control portion(not shown). When the electrical control portion causes the electricalpump 22 to be operated, water circulates from the electrical pump 22, toa water passage 12 a of a water-refrigerant heat exchanger 12, the waterstorage tank 21, and the electrical pump 22, in this order.

Next, the refrigerant cycle device 10 will be described. The refrigerantcycle device 10 includes the compressor 11 configured to draw andcompress the refrigerant and to discharge the compressed refrigerant.For example, the compressor 11 is an electrical compressor that includesa compression mechanism 11 a having a fixed discharge capacity, and anelectrical motor 11 b for driving the compression mechanism 11 a. As thecompression mechanism 11 a, various-type compression mechanisms such asa scroll type, a vane type, a rolling-piston type may be used.

Because the operation of the electrical motor 11 b, such as therotational speed of the electrical motor 11 b, is controlled by usingthe control signal output from the electrical control portion, analternate current motor or a direct current motor may be used. Bycontrolling the rotational speed of the electrical motor 11 b, therefrigerant discharge capacity (displacement) of the compressionmechanism 11 a can be changed. Thus, the electrical motor 11 b can beused as a discharge capacity varying portion for varying the refrigerantdischarge capacity of the compression mechanism 11 a.

A refrigerant passage 12 b of the water-refrigerant heat exchanger 12 isconnected to the refrigerant discharge side of the compressor 11. Thewater-refrigerant heat exchanger 12 is a heat exchanger having thereinthe refrigerant passage 12 b through which high-temperature andhigh-pressure refrigerant discharged from the compressor 11 flows, andthe water passage 12 a through which water flows to perform heatexchange with the refrigerant flowing through the refrigerant passage 12b. Thus, heat of the high-temperature and high-pressure refrigerantdischarged from the compressor 11 is radiated to the water in thewater-refrigerant heat exchanger 12, so that the water is heated and therefrigerant is cooled in the water-refrigerant heat exchanger 12. In thepresent embodiment, the water-refrigerant heat exchanger 12 is arefrigerant radiator for cooling the refrigerant discharged from thecompressor 11.

In the present embodiment, because the refrigerant cycle device 10 isoperated with a super-critical refrigerant state, the refrigerant (e.g.,carbon dioxide) is not condensed while passing through the refrigerantpassage 12 b of the water-refrigerant heat exchanger 12.

A branch portion 13 is connected to an outlet side of the refrigerantpassage 12 b of the water-refrigerant heat exchanger 12 such thathigh-pressure refrigerant flowing from the refrigerant passage 12 b isbranched by the branch portion 12 into first and second streams. Thebranch portion 13 is a three-way joint having a single refrigerant inletand two refrigerant outlets. The three-way joint may have different pipediameters or may have the same pipe diameter. The branch portion 13 maybe formed from a metal black or a resin block having therein pluralrefrigerant passages.

One end of a first refrigerant pipe 14 a is connected to one refrigerantoutlet of the branch portion 13, and the other end of the firstrefrigerant pipe 14 a is connected to a refrigerant inlet side of anozzle 151 of the ejector 15, so that the refrigerant of the firststream branched at the branch portion 13 flows into the refrigerantinlet side of the nozzle 151 of the ejector 15 through the firstrefrigerant pipe 14 a. One end of a second refrigerant pipe 14 b isconnected to the other refrigerant outlet of the branch portion 13, andthe other end of the second refrigerant pipe 14 b is connected to arefrigerant inlet side of an electrical expansion valve 17, so that therefrigerant of the second stream branched at the branch portion 13 flowsinto the refrigerant inlet side of the electrical expansion valve 17through the second refrigerant pipe 14 b.

The ejector 15 is used as a refrigerant decompression portion fordecompressing the refrigerant at the nozzle 151, and as a kinetic energypumping portion for circulating the refrigerant by using the suctionaction of the jet refrigerant jetted from the nozzle 151. Next, thedetail structure of the ejector 15 will be described with reference toFIG. 2.

As shown in FIG. 2, the ejector 15 includes the nozzle 151, a bodyportion 152, a diffuser 153, a needle 154, a driving portion 155 or thelike. The nozzle 151 is configured so as to decompress the refrigerantflowing into the interior of the nozzle 151 through the firstrefrigerant pipe 14 a in iso-entropy. The nozzle 151 can be formed froma metal member having an approximately cylindrical shape by drilling orcutting or the like. For example, the nozzle 151 may be made of astainless steel, for example.

For example, the nozzle 151 is formed by coaxially combining twocylindrical members having different diameters. That is, the nozzle 151includes a large-diameter portion 151 a, and a small-diameter portion151 b. The outer peripheral surface of the large-diameter portion 151 ais press-fitted into the body portion 152. The large-diameter portion151 a is provided with a nozzle inlet port 151 d through which therefrigerant flowing from the first refrigerant pipe 14 a flows into arefrigerant passage 151 c provided in the nozzle 151.

The refrigerant passage 151 c is provided in the nozzle 151 such thatthe refrigerant flows through the refrigerant passage 151 c from a sideof the large-diameter portion 151 a to a side of the small-diameterportion 151 b. Furthermore, the refrigerant passage 151 c extends in theaxial direction of the nozzle 151 such that the refrigerant passage areaof the refrigerant passage 151 c of the nozzle 151 is gradually reducedin a downstream portion (i.e., the side of the small-diameter portion151 b) of the refrigerant passage 151 c. Thus, the refrigerant passingthrough the refrigerant passage 151 c is decompressed in thesmall-diameter portion, and the decompressed refrigerant is jetted asshown by the arrow 100 from a refrigerant jet port 151 e that isprovided at the most downstream position of the refrigerant passage 151c.

The needle 154 is located in the refrigerant passage 151 c of the nozzle151 such that the refrigerant passage area of the refrigerant passage151 c is changed in accordance with a displacement of the needle 154 inthe axial direction of the nozzle 151. The needle 154 is a needle-likemember that extends coaxially with the nozzle 151. The needle 154 can beformed by cutting a cylindrical metal member such as a stainless steelmember.

The needle 154 has a tip end portion tapered downstream in a refrigerantjet direction, on a side of the refrigerant jet port 151 e of the nozzle151. The tip end portion of the needle 154 extends from the refrigerantjet port 151 e of the nozzle 151 by a dimension to a downstream side.Thus, when the needle 154 is displaced, the refrigerant passage area ofthe refrigerant passage 151 c and the open area of the refrigerant jetport 151 e are changed. The other end portion of the needle 154 oppositeto the tapered tip end portion is provided with a screw portion (e.g.,male screw portion) to which the driving portion 155 is connected.

The driving portion 155 is, for example, a motor actuator for drivingand displacing the needle 154, and is configured to have a coil 155 a, arotor 155 b and a can 155 c. The coil 155 a is configured to generate arotation magnetic force in accordance with a control signal output fromthe electrical control portion, so that the rotor 155 b can be rotatedaround the axial of the nozzle 151.

A screw 158 is fitted into the nozzle 151, and the needle 154 isslidably inserted into an inner diameter portion of the screw 158. Oneend portion of the needle 154 on a side of the driving portion 155 isconnected to the rotor 155 b via a washer 156. The rotor 155 b has acylinder that is provided with a female screw portion on its inner side,and the female screw portion of the rotor 155 b is screwed with a malescrew provided on an outer peripheral surface of the screw 158. Thus,when the rotor 155 b rotates, the rotator 155 b and the needle 154displace in the axial direction of the needle 154. The can 155 c is ametal cup-like can 155 c made of a non-magnetic metal, and is a housingmember for housing the rotor 155 b. The can 155 c is welded and fixed toone end side of the body portion 152 in the axial direction. A spring157 is disposed between the washer 156 and the screw 158, and is biasedto push the rotor 155 b in an axial direction opposite to the nozzleside.

The nozzle 151 and the driving portion 155 are fixed to the body portion152. The body portion 152 has therein various open holes through whichthe refrigerant flows into or flows out of the interior of the bodyportion 152, and various refrigerant passages respectively communicatingwith the various open holes. The body portion 152 can be formed from acylindrical metal member by cutting and drilling.

An outlet of the diffuser 153 is coupled to a refrigerant inlet side ofa first evaporator 15 as described later. The various open holesprovided in the body portion 152 are a refrigerant inlet portion 152 acommunicating with the nozzle inlet port 151 d of the nozzle 151, arefrigerant suction port 152 b from which refrigerant flowing out of asuction side evaporator (i.e., second evaporator) 18 is drawn, and arefrigerant outlet port 152 c from which the refrigerant drawn from therefrigerant suction port 152 b and the refrigerant jetted from therefrigerant jet port 151 e flow out as a mixed refrigerant.

The refrigerant inlet port 152 a is located at an outer peripheral sideof the large-diameter portion 151 a of the nozzle 151, and is open in adirection perpendicular to the axial direction of the nozzle 151. Thefirst refrigerant pipe 14 a is connected to the refrigerant inlet port152 a so that the refrigerant flowing into the first refrigerant pipe 14a from the branch portion 13 flows into the nozzle inlet port 151 d.

The refrigerant suction port 152 b is located in the body portion 152 atan outer peripheral side of the small-diameter portion 151 b of thenozzle 151, and is open in a direction perpendicular to the axialdirection of the nozzle 151. Thus, the flow direction of the refrigerantdrawn from the refrigerant suction port 152 b is not vertically crossedwith the jet direction of the jet refrigerant jetted from therefrigerant jet port 151 e of the nozzle 151. A third refrigerant pipe14 c (suction pipe) connected to the refrigerant outlet side of thesecond evaporator 18 is connected to the refrigerant suction port 152 bso that the refrigerant flowing out of the second evaporator 18 is drawninto the refrigerant suction port 152 b through the third refrigerantpipe 14 c.

The refrigerant outlet port 152 c is arranged coaxially with the nozzle151, and is open in the axial direction of the nozzle 151. The diffuser153 is connected to the refrigerant outlet port 152 c of the bodyportion 152. The first refrigerant pipe 14 a, the third refrigerant pipe14 c and the diffuser 153 may be respectively formed from a metal pipesuch as a copper pipe, and can be bonded respectively to the bodyportion 152 by brazing or the like.

The various refrigerant passages provided in the body portion 152includes a refrigerant suction passage 152 d through which therefrigerant drawn from the refrigerant suction port 152 b is introducedtoward the refrigerant injection port 151 e of the nozzle 151, and acylindrical mixing passage 152 e provided continuously for therefrigerant suction passage 152 d, through which the mixed refrigerantis introduced to the refrigerant outlet port 152 c. Here, the mixedrefrigerant is a mixture of the refrigerant jetted from the refrigerantjet port 151 e and the refrigerant drawn from the refrigerant suctionport 152 b.

The refrigerant suction passage 152 d is configured by a suction inletpart 152 f from which the suction refrigerant from the refrigerantsuction port 152 b flows, a suction space part 152 g through which thesuction refrigerant introduced from the suction inlet part 152 f flows,and a suction outlet part 152 h through which the suction refrigerantfrom the suction space part 152 g flows into the mixing passage 152 e.

The suction inlet part 152 f is open in the same direction as therefrigerant suction port 152 b, such that the passage open area of thesuction inlet part 152 f is smaller than the passage open area of therefrigerant suction port 152 b. For example, in the present embodiment,a ratio of the passage open area of the suction inlet part 152 f to theopen area of the refrigerant suction port 152 b can be set equal to orsmaller than 0.5.

As shown in FIG. 2, the passage open area of the suction inlet part 152f is greatly smaller than the maximum passage open area of the thirdrefrigerant pipe 14 c (suction refrigerant pipe). In the presentembodiment, the suction inlet part 152 f is configured by an orifice.The suction inlet part 152 f may be configured by directly forming anorifice in the body portion 152, or may be configured by fitting anothermember having an orifice into the body portion 152.

The suction space part 152 g is approximately a cylindrical spaceprovided at an outer peripheral side of the small-diameter portion 151 bof the nozzle 151. The suction refrigerant flowing from the suctioninlet part 152 f changes its flow direction in the suction space part152 g while passing through the suction space part 152 g. Therefrigerant passage area (i.e., passage cross-sectional area) of thesuction space part 152 g is larger than the refrigerant passage area(i.e., passage cross-sectional area) of the suction inlet part 152 f.

That is, the refrigerant passage area of the suction space part 152 g isa cross sectional area of the suction space part 152 g in a crosssection perpendicular to the flow direction of the refrigerant flowingthrough the suction space part 152 g. Therefore, if the flow directionof the suction refrigerant flowing through the suction space part 152 gis changed, the refrigerant passage area of the suction space part 152 gis also changed.

In the present embodiment, the smallest refrigerant passage area in therefrigerant passage area of the suction space part 152 g is set largerthan the refrigerant passage area of the suction inlet part 152 f. Thatis, the refrigerant passage area of the suction inlet part 152 f becomessmaller than the smallest refrigerant passage area of the suction spacepart 152 g. For example, a ratio of the refrigerant passage area of thesuction inlet part 152 f to the smallest refrigerant passage area of thethird refrigerant pipe 14 c (suction refrigerant pipe) is equal to orsmaller than 0.5.

The suction outlet part 152 h is open in the axial direction of thenozzle 151, i.e., is open in the jet direction (arrow 100 in FIG. 2) ofthe jet refrigerant jetted from the refrigerant jet port 151 e, suchthat the refrigerant in the suction space part 152 g flows out of thesuction outlet part 152 h as in the jet direction shown by arrow 100 inFIG. 2.

The suction outlet part 152 h is provided to have a refrigerant passagearea that is smaller than the smallest refrigerant passage area of thesuction space part 152 g. As an example, a ratio of the refrigerantpassage area of the suction outlet part 152 h to the smallestrefrigerant passage area of the suction space part 152 g is set equal toor smaller than 0.5.

The nozzle 151 is located such that the tip end portion of thesmall-diameter portion 151 b of the nozzle 151 can penetrate into theaxial center part of the suction outlet part 152 h. Therefore, thesuction outlet part 152 h has a ring-shaped passage around the tip endportion of the small-diameter portion 151 b of the nozzle 151.

The diffuser 153 is a pressurizing portion in which the flow speed ofthe refrigerant is decelerated and the pressure of the refrigerant isincreased, in the ejector 15. The diffuser 153 can be formed byplastically deforming a metal pipe (copper pipe) such that therefrigerant passage area of the diffuser 153 is gradually increased astoward downstream. Thus, the refrigerant is decelerated and the pressureof the refrigerant is increased in the diffuser 153 so that the speedenergy of the refrigerant is converted to the pressure energy of therefrigerant. As shown in FIG. 2, the refrigerant passage area is madesubstantially constant at the inlet side and the outlet side of thediffuser 153. As shown in FIG. 1, the refrigerant outlet side of thediffuser 153 is connected to the refrigerant inlet side of the firstevaporator 16.

For example, the first evaporator 16 is a heat absorption heat exchangerin which the refrigerant flowing thereinto from the diffuser 153 isevaporated by absorbing heat from outside air blown by a blower fan 16a. That is, the refrigerant flowing into the first evaporator 16 fromthe diffuser 153 is heat-exchanged with outside air blown by the blowerfan 16 a, to be evaporated. The blower fan 16 a may be an electricalblower in which the fan rotational speed is controlled by the controlvoltage output from the electrical control portion. The refrigerantoutlet side of the first evaporator 16 is coupled to the refrigerantsuction port of the compressor 11.

As shown in FIG. 1, an electrical expansion valve 17 is connected to thesecond refrigerant pipe 14 b so that the second stream of therefrigerant branched at the branch portion 13 flows into the electricalexpansion valve 17 through the second refrigerant pipe 14 b. Theelectrical expansion valve 17 is a decompression unit configured todecompress and expand the refrigerant flowing into the secondrefrigerant pipe 14 b. The operation of the electrical expansion valve17 can be controlled by control signal output from the electricalcontrol portion. As shown in FIG. 1, the electrical expansion valve 17includes a valve portion 17 a, and a motor portion 17 b for controllinga valve open degree of the valve portion 17 a. The valve open degree ofthe valve portion 17 a is controlled by the motor portion 17 b based onthe control signal output from the electrical control portion.

The second evaporator 18 (suction evaporator) is connected to arefrigerant outlet side of the valve portion 17 a of the electricalexpansion portion 17. For example, the second evaporator 18 is a heatabsorption heat exchanger in which the refrigerant flowing thereintofrom the electrical expansion valve 17 is evaporated by absorbing heatfrom outside air after passing through the first evaporator 16 and blownby the blower fan 16 a. That is, the refrigerant flowing into the secondevaporator 18 from the electrical expansion valve 17 is heat-exchangedwith outside air blown by the blower fan 16 a, to be evaporated. In FIG.1, the second evaporator 18 is located downstream from the firstevaporator 16 in the air flow direction 200; however, the secondevaporator 18 can be located separately from the first evaporator 16.The refrigerant outlet side of the second evaporator 18 is coupled tothe refrigerant suction port 152 b of the ejector 15 via the thirdrefrigerant pipe 14 c.

In the example of FIG. 1, the first evaporator 16 and the secondevaporator 18 are configured by an integrated heat exchange unit with afin and tube structure. For example, the first evaporator 16 and thesecond evaporator 18 are configured to have common heat exchange finswhile having independent tube structures. In the integrated structure ofthe first evaporator 16 and the second evaporator 18, the tube structurein which the refrigerant flowing out of the ejector 15 flows and thetube structure in which the refrigerant flowing out of the electricalexpansion valve 17 flows are provided independently from each other.

Thus, the heat of the air blown by the blower fan 16 a is absorbed firstby the refrigerant at the first evaporator 16, and then is absorbed bythe refrigerant at the second evaporator 18.

In the example of FIG. 1, the first evaporator 16 and the secondevaporator 18 are arranged in series in the air flow direction 200, tobe integrated. However, the first evaporator 16 and the secondevaporator 18 separated from each other may be arranged in series in theair flow direction 200. Alternatively, the first evaporator 16 and thesecond evaporator 18 may be arranged separately from each other atdifferent places.

Next, the electrical control portion of the refrigerant cycle deviceaccording to the first embodiment will be described. The electricalcontrol portion is a control device configured by a microcomputer havingtherein a CPU, a ROM and a RAM and the like, and circumference circuits,which are generally known. The output side of the electrical controlportion is connected to various actuators such as the electrical motor11 b of the compressor 11, the driving portion 155 of the ejector 15, amotor of the blower fan 16 a, the electrical motor 17 b of theelectrical expansion valve 17, and the like, so as to control thecomponents.

The input side of the electrical control portion is connected to asensor group, an operation panel and the like. The sensor group includesa water temperature sensor configured to detect a temperature of theheated water at the water outlet side of the water passage 12 a of thewater-refrigerant heat exchanger 12, an outside air temperature sensorconfigured to detect a temperature of air (e.g., outside air) blown bythe blower fan 16 a. The operation panel is connected to the input sideof the electrical control portion so that operation signals such as astart signal and a stop signal of the water heater 1 and a watertemperature setting signal of the water heater 1 are input to theelectrical control portion.

Next, operation of the heat pump water heater 1 according to the firstembodiment will be described. When electrical power is supplied from anexterior of the heat-pump water heater 1 and an operation start signalof the water heater 1 is input from the operation panel to theelectrical control portion, the electrical control portion performs apredetermined control program stored in the ROM, and thereby thecomponents 11 b, 155, 16 a, 17, 22 and the like of the refrigerant cycledevice 10 are operated.

High-temperature and high-pressure refrigerant discharged from thecompressor 11 flows into the refrigerant passage 12 b of thewater-refrigerant heat exchanger 12 to perform heat exchange with waterflowing into the water passage 12 a of the water-refrigerant heatexchanger 12 from a lower side in the water tank 21. Water is introducedby the electrical pump 22 from the lower side in the water tank 21 intothe water passage 12 a, and is heat-exchanged with the high-temperaturehigh-pressure refrigerant flowing through the refrigerant passage 12 bin the water-refrigerant heat exchanger 12. Thus, water is heated whilepassing through the water passage 12 a of the water-refrigerant heatexchanger 12, and the heated water is stored at an upper side in thewater tank 21.

The high-pressure refrigerant flowing out of the refrigerant passage 12b of the water-refrigerant heat exchanger 12 flows into the refrigerantbranch portion 13 and is branched into the first stream and the secondstream. The refrigerant of the first stream branched at the branchportion 13 flows into the nozzle portion 151 of the ejector 15 via thefirst refrigerant pipe 14 a, and is decompressed in the nozzle 151 iniso-entropy. The refrigerant decompressed in iso-entropy in the nozzle151 is jetted from the refrigerant jet port 151 e by a high speed.

The driving portion 155 of the ejector 15 is controlled by controlsignal output from the electrical control portion so as to control therefrigerant passage areas of the refrigerant passage 151 c and therefrigerant jet port 151 e of the ejector 15, such that the super-heatdegree of the refrigerant drawn into the compressor 11 is approached toa predetermined value. Thus, it can prevent liquid refrigerant frombeing returned to the compressor 11.

The refrigerant flowing out of the second evaporator 18 is drawn intothe ejector 15 from the refrigerant suction port 152 b. Furthermore, thejet refrigerant jetted from the refrigerant jet port 151 e and thesuction refrigerant drawn from the refrigerant suction port 152 b aremixed at an inlet side of the mixing passage 152 e and the mixingpassage 152 e, and then the mixed refrigerant flows into the diffuser153.

Because the passage area of the diffuser 153 is gradually increasedtoward downstream, the refrigerant pressure is increased by convertingthe speed energy of the refrigerant to the pressure energy of therefrigerant. The refrigerant flowing out of the diffuser 153 of theejector 15 flows into the first evaporator 16 and is evaporated byabsorbing heat from outside air blown by the blower fan 16 a. Then, therefrigerant flowing out of the first evaporator 16 is drawn into thecompressor 11 and is compressed in the compressor 11.

The refrigerant of the second stream branched at the branch portion 13is decompressed and expanded at the electrical expansion valve 17, andthen flows into the second evaporator 18. The refrigerant flowing intothe second evaporator 18 is evaporated by absorbing heat from theoutside air, and the evaporated gas refrigerant flowing out of thesecond evaporator 18 is drawn into the ejector 15 from the refrigerantsuction port 152 b.

The throttle passage area (i.e., valve open degree) of the electricalexpansion valve 17 is changed in accordance with a control signal outputfrom the electrical control portion, such that the refrigerant pressureon the high pressure side of the refrigerant cycle before beingdecompressed is approached to a target pressure. The target pressure isdetermined based on the temperature of the refrigerant flowing out ofthe refrigerant passage 12 b of the water-refrigerant heat exchanger 12such that the coefficient of performance (COP) of the refrigerant cycleis approached to approximately the maximum value. Thus, the refrigerantcycle device 10 can be operated with a high value of the COP.

In the refrigerant cycle device 10, the refrigerant pressurized in thediffuser 153 flows into the first evaporator 16. In contrast, becausethe second evaporator 18 is connected to the refrigerant suction port152 b, the refrigerant evaporation pressure in the second evaporator 18corresponds to the lowest pressure immediately after the refrigerant jetport 151 e of the nozzle 151.

Thus, the refrigerant evaporation pressure (refrigerant evaporationtemperature) in the second evaporator 18 can be made lower than therefrigerant evaporation pressure (refrigerant evaporation temperature)in the first evaporator 16. As a result, even when the second evaporator18 is located downstream from the first evaporator 16 in the air flowdirection 200, a suitably temperature difference between the refrigerantand air blown by the blower fan 16 a can be set at both the firstevaporator 16 and the second evaporator 18, and thereby the refrigerantcan effectively absorb heat from air at both the first evaporator 16 andthe second evaporator 18.

In the present embodiment, the refrigerant suction passage 152 d isconfigured by the suction inlet part 152 f, the suction space part 152 gand the suction outlet part 152 h. Next, the configuration of theejector 15 including the refrigerant suction passage 152 d will bedescribed.

In the present embodiment, because the refrigerant passage area of thesuction inlet part 152 f is made smaller than the open area of therefrigerant suction port 152 b, a flow speed of the suction refrigerantflowing from the suction inlet part 152 f to the suction space part 152g can be increased than a flow speed of the suction refrigerant drawnthrough the refrigerant suction port 152 b. Thus, it is possible toeffectively increase the dynamical pressure of the suction refrigerantflowing into the suction space part 152 g from the suction inlet part152 f.

Because the refrigerant flowing into the suction space part 152 g isdisturbed due to the dynamical pressure, the refrigerant flowing intothe suction space part 152 g can be effectively mixed to be uniform.Furthermore, because the flow speed of the suction refrigerant (suctionfluid) after flowing into the suction space part 152 g is decreased thanthe flow speed of the suction refrigerant (suction fluid) at the time ofjust flowing into the suction space part 152 g from the suction inletpart 152 f, the dynamical pressure of the suction refrigerant isconverted to the static pressure. Thus, the suction space part 152 g canbe used for equalizing the pressure of the refrigerant flowing out ofthe suction outlet part 152 h, and thereby the flow speed difference inthe flow speed distribution can be reduced.

Furthermore, because the flow passage area (i.e., flow passage sectionalarea) of the suction outlet part 152 h is smaller than that of thesuction space part 152 g, it can prevent the refrigerant from flowingout of the suction outlet part 152 h before the flow speed difference inthe flow speed distribution is reduced.

Accordingly, the mixing pressure loss caused while the jet refrigerantand the suction refrigerant are mixed can be reduced, thereby thepressurizing amount in the mixing passage 152 e and the diffuser 153 canbe increased. Thus, the power consumed in the compressor 11 can bereduced, thereby increasing the COP in the refrigerant cycle.

In the present embodiment, because the suction inlet part 152 f isconfigured by an orifice, the flow speed of the refrigerant flowing fromthe suction inlet part 152 f into the suction space part 152 g can beeffectively made faster than the flow speed of the refrigerant drawnfrom the refrigerant suction port 152 b into the suction inlet part 152f. Therefore, the length of the refrigerant suction passage 152 d can berelatively reduced.

Because the cylindrical suction space part 152 g is provided at an outerperipheral side of the nozzle 151, the suction refrigerant can beuniformly mixed in the entire outer peripheral side of the jetrefrigerant, thereby effectively reducing the mixing pressure loss.

The suction outlet part 152 h communicating with the cylindrical suctionspace part 152 g around the small-diameter portion 151 b of the nozzle151 is provided upstream of the mixing passage 152 e, and therefrigerant jet port 151 e of the nozzle 151 is located at the radialcenter area of the suction outlet part 152 d. Therefore, the refrigerantdrawn from the suction inlet part 152 f is turned in the cylindricalsuction space part 152 g and then flows to the suction outlet part 152h. Thus, a flow direction of the refrigerant from the suction space part152 g into the suction outlet part 152 h substantially corresponds tothe jet direction 100 of the refrigerant jetted from the refrigerant jetport 151 e into the mixing passage 152 e via the suction outlet part 152h. Accordingly, the mixing pressure loss can be more effectivelyreduced.

In the first embodiment, the present invention is applied to the ejector15 in which the flow direction of the suction refrigerant drawn from therefrigerant suction port 152 b is substantially crossed perpendicularlywith an extension line of the jet direction 100 of the refrigerantjetted from refrigerant jet port 151 e. In this case, the mixingpressure loss, caused while the jet refrigerant and the suctionrefrigerant are mixed in the ejector 15, can be more effectivelyreduced.

Second Embodiment

A second embodiment of the present invention will be described withreference to FIG. 3. In the above-described first embodiment, the thirdrefrigerant pipe (suction refrigerant pipe) 14 c connected to therefrigerant suction port 152 b is a general pipe having a constantpassage area. However, in the second embodiment, as shown in FIG. 3, thethird refrigerant pipe (suction refrigerant pipe) 14 c connected to therefrigerant suction port 152 b is configured to have a passage sectionalarea gradually reduced toward the refrigerant suction port 152 b.

In the second embodiment, the passage sectional area of the suctioninlet part 152 f is made smaller than the passage sectional area of thethird refrigerant pipe 14 c. Thus, the passage sectional area of thesuction inlet part 152 f is smaller than the maximum passage sectionalarea of the third refrigerant pipe 14 c. As an example of the secondembodiment, the passage sectional area of the suction inlet part 152 fcan be made smaller than the minimum passage sectional area of the thirdrefrigerant pipe 14 c. In the second embodiment, the other parts of theejector 15 can be similar to those of the ejector 15 of the firstembodiment.

According to the second embodiment of the present invention, when theheat pump water heater 1 is operated, the flow speed of the refrigerantpassing through the third refrigerant pipe 14 c is gradually increasedas toward the refrigerant suction port 152 b. Thus, the dynamicalpressure of the refrigerant flowing from the suction inlet port 152 finto the suction space part 152 g can be increased.

As a result, a difference of the flow speed in the flow speeddistribution of the suction refrigerant flowing out of the suctionoutlet part 152 h can be reduced, thereby reducing the mixing pressureloss caused while the jet refrigerant and the suction refrigerant aremixed. Furthermore, the flow speed of the refrigerant flowing throughthe third refrigerant pipe 14 c is gradually increased, thereby reducingthe noise generation.

Although the present invention has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications will become apparent to those skilled in the art.

In the ejector 15 of the above-described embodiments, the flow directionof the suction refrigerant drawn from the refrigerant suction port 152 bis crossed perpendicularly with the extension line of the jet direction100 of the jet refrigerant jetted from the refrigerant jet port 151 e ofthe nozzle 151. However, the flow direction of the suction refrigerantdrawn from the refrigerant suction port 152 b and the jet direction 100of the jet refrigerant jetted from the refrigerant jet port 151 e of thenozzle 151 may be set at directions to be different from each other.

For example, because the flow direction of the suction refrigerantflowing from the suction inlet part 152 f is changed in the suctionspace part 152 g and then the refrigerant in the suction space part 152g flows out of the suction outlet part 152 h, the mixing pressure losscan be effectively reduced.

In the above-described embodiments, the refrigerant passage area of thenozzle 151 is changed such that the super-heat degree of the refrigeranton the refrigerant outlet side of the first evaporator 16 becomes in atarget super-heat degree, and the throttle passage area of theelectrical expansion valve 17 is changed such that the refrigerantpressure on the high-pressure side in the refrigerant cycle becomes atarget value. However, the control of the nozzle 151 and the control ofthe electrical expansion valve 17 can be performed reversely.

That is, the throttle passage area of the electrical expansion valve 17can be changed such that the super-heat degree of the refrigerant on therefrigerant outlet side of the first evaporator 16 becomes in the targetsuper-heat degree, and the refrigerant passage area of the nozzle 151 ischanged such that the refrigerant pressure on the high-pressure side inthe refrigerant cycle becomes a target value.

In the above-described embodiments, the carbon dioxide is used as therefrigerant. However, a generally known fluid such as carbon hydriderefrigerant, a flon-based refrigerant can be used. Furthermore, theejector 15 of the above-described embodiments can be used for asub-critical refrigerant cycle device in which the refrigerant pressureon the high-pressure side is lower than the critical pressure of therefrigerant.

In the above-described embodiments, an electrical compressor is used asthe compressor 11. However, a generally known compressor such as acompressor driven by the engine or the like may be used as thecompressor 11. Furthermore, as the compression mechanism 11 a, afixed-displacement compression mechanism or a variable-displacementcompression mechanism may be used.

In the above-described embodiments, the nozzle 151 is a variable nozzleconfigured such that the refrigerant passage of the nozzle 151 can bechanged. However, the nozzle 151 may be not a variable nozzle configuredsuch that the refrigerant passage of the nozzle 151 is fixed.

In the above-described embodiments, the refrigerant cycle device 10 isused for the heat-pump water heater 1. However, the refrigerant cycledevice 10 may be used for a fixed-type air conditioner, a vehicle airconditioner or the like. In this case, the first evaporator 16 and thesecond evaporator 18 can be used as an interior heat exchanger, and aradiator (12) is used as an exterior heat exchanger.

Such changes and modifications are to be understood as being within thescope of the present invention as defined by the appended claims.

1. An ejector comprising: a nozzle configured to decompress and jet afluid; a body portion having a fluid suction port from which a fluid isdrawn by a jet flow of the fluid jetted from the nozzle, and a fluidsuction passage through which the fluid drawn from the fluid suctionport flows while a flow direction of the fluid drawn from the fluidsuction port is changed; and a pressurizing portion in which a pressureof a fluid mixture between the fluid flowing through the fluid suctionpassage from the fluid suction port and the fluid jetted from the nozzleis increased, wherein the fluid suction passage is configured to have asuction inlet part into which the fluid from the fluid suction portflows, a suction space part in which the flow direction of the fluidflowing from the fluid suction port is changed, and a suction outletpart from which the fluid from the suction space part flows out in a jetdirection of the jet fluid, the suction inlet part has a fluid passagearea that is smaller than an open area of the fluid suction port and afluid passage area of the suction space part, and the fluid passage areaof the suction outlet part is smaller than the fluid passage area of thesuction space part.
 2. The ejector according to claim 1, wherein thefluid suction port is connected to a fluid suction pipe in which thefluid to be drawn into the fluid suction port flows, and the fluidpassage area of the suction inlet part is smaller than a fluid passagearea of the fluid suction pipe.
 3. The ejector according to claim 2,wherein the fluid passage area of the fluid suction pipe is graduallyreduced as toward the fluid suction port.
 4. The ejector according toclaim 1, wherein the suction inlet part is an orifice.
 5. The ejectoraccording to claim 1, wherein an extending line of a flow direction ofthe fluid drawn from the fluid suction port is crossed perpendicularlywith an extending line of the jet direction of the fluid jetted from thenozzle.
 6. The ejector according to claim 1, wherein the suction spacepart is provided on an outer peripheral side of the nozzle.
 7. Theejector according to claim 1, wherein a ratio of the fluid passage areaof the suction inlet part to the open area of the fluid suction port isequal to or smaller than 0.5.
 8. The ejector according to claim 2,wherein a ratio of the fluid passage area of the suction inlet part tothe maximum fluid passage area of the fluid suction pipe is equal to orsmaller than 0.5.
 9. The ejector according to claim 1, wherein a ratioof the fluid passage area of the suction outlet part to the fluidpassage area of the suction space part is equal to or smaller than 0.5.10. The ejector according to claim 1, wherein the suction space part isan approximately cylindrical passage provided on the outer peripheralside of the nozzle to extend in an axial direction of the nozzle, andthe suction outlet part extends coaxially with the cylindrical passageof the suction space part and is tapered downstream.
 11. The ejectoraccording to claim 10, wherein the nozzle is located to protrude intothe suction outlet part from the suction space part coaxially with thecylindrical passage, and the suction inlet part is open to thecylindrical passage in a direction approximately perpendicular to theaxial direction of the nozzle.
 12. The ejector according to claim 1,further comprising a cylindrical mixing passage provided between thesuction outlet part and the diffuser coaxially.
 13. An ejectorcomprising: a nozzle configured to decompress and jet a fluid; a bodyportion having a fluid suction port from which a fluid is drawn by a jetflow of the fluid jetted from the nozzle, and a fluid suction passagethrough which the fluid drawn from the fluid suction port flows while aflow direction of the fluid drawn from the fluid suction port ischanged; and a pressurizing portion in which a pressure of a fluidmixture between the fluid flowing through the fluid suction passage fromthe fluid suction port and the fluid jetted from the nozzle isincreased, wherein the fluid suction port is connected to a fluidsuction pipe in which the fluid to be drawn into the fluid suction portflows, the fluid suction passage is configured to have a suction inletpart into which the fluid from the fluid suction port flows, a suctionspace part in which the flow direction of the fluid flowing from thefluid suction port is changed, and a suction outlet part from which thefluid from the suction space part flows out in a jet direction of thejet fluid, the suction inlet part has a fluid passage area that issmaller than a fluid passage area of the fluid suction pipe and a fluidpassage area of the suction space part, and the fluid passage area ofthe suction outlet part is smaller than the fluid passage area of thesuction space part.
 14. The ejector according to claim 13, wherein thefluid passage area of the fluid suction pipe is gradually reduced astoward the fluid suction port, and the fluid passage area of the suctioninlet part is smaller than the smallest fluid passage area of the fluidsuction pipe.